Manuscript received June 21, 2017; revised September 3, 2017; accepted October 17, 2017. Date of publication January 5, 2018; date of current version February 8, 2018. This work was supported in part by the National Nature Science Foundation of China under Grant 61771191, in part by the Natural Science Foundation of Hunan Province under Grant 2017JJ2052, in part by the Ministry of Education Cooperative Education Project under Grant 201601004010 and 201701056026, and in part by the Graduate Innovation Project of Hunan Province under Grant CX2017B112. The Associate Editor coordinating the review process was Dr. Ruqiang Yan. (Corresponding author: Hongli Liu.) C. Wang is with the College of Electrical and Information Engineering, Hunan University, Changsha 410082, China, and also with the College of Electrical Engineering, University of South China, Hengyang 421001, China (e-mail: chao_wang@hnu.edu.cn).
